At the nub of all those worries, of course, is how much people share on Facebook, with whom and — perhaps most important — how well they understand the potential consequences.

The company has struggled to find a balance between giving users too little control over privacy and giving them too much, for fear they won’t share much at all. Seeking a happy medium, Facebook announced changes on Tuesday that it says will help users get a grip on what they share.

When the changes are introduced on Thursday, every time Facebook users add a picture, comment or any other content to their profile pages, they can specify who can see it: all of their so-called Facebook friends, a specific group of friends, or everyone who has access to the Internet. These will be indicated by icons that replace the current, more complicated padlock menu.

Similar controls will apply to information like users’ phone numbers and hometowns and whether they like, say, death metal bands, on their profile pages. Users will no longer have to seek out a separate privacy page to tweak who sees how much of that personal information. Nor will they have to bother to remember what those settings were.

Company officials say they hope the changes will simplify the process of establishing who knows what about your life on the Internet — and hopefully, save a few people the embarrassment of unwittingly sharing too much.

“We want to make this stuff unmistakably clear,” Chris Cox, vice president for product at Facebook, said in an interview. “It has to be clear that Facebook is a leader in how people control who sees what.”

Implicit in these changes is the challenge brought on by Facebook’s own success. It is used by 750 million people worldwide, with varying degrees of knowledge about what it means to have a life online. There is the looming prospect that the company will go public, along with the abiding concern about potential government regulation or litigation stemming from privacy issues.

Not least, there is the need for Facebook to cultivate the trust of its users, amid growing competition from Google’s nascent social networking service, Google Plus, which emphasizes more compartmentalized communications with different sets of friends and acquaintances.

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Privacy advocates warned that the new tools did not address a concern about sharing location. One Facebook user can publish information about another user’s whereabouts without his or her consent — whether it’s an employee at the beach on the day he or she called in sick or a husband at a strip club without his wife’s knowledge.

Other privacy experts say that if users believe they have control over who sees what, they are more likely to share.

“I think it’s part of an evolution to push back at the notion that Facebook is trying to trick you into sharing,” said Jules Polonetsky of the Future of Privacy Forum, which is based in Washington. “You’re more likely to do so when you know what you’re doing.”